从 char 赋值到 char * 使指针中的整数不带大小写

问：

我需要制作一个程序，根据输入对任意数量的学生进行计算和评分。我还需要在评分后打印前 3 名学生，并以 Letter 格式显示最终成绩。我想知道我在字母等级中做错了什么，因为这一直作为一个错误弹出：字母等级错误

这是我到目前为止的代码：

#include <stdio.h>

struct student {
    char firstName[50], lastName[50], equigrade;
    int q1, q2, q3, q4, q5, midterms, finals;
    float FinalGrade;
} s[15];

int main() {
    int i, n, q1, q2, q3, q4, q5, midterms, finals, TotalQuiz;
    float QuizGrade, MidtermExamGrade, FinalExamGrade, FinalGrade;
    printf("Enter number of students:");
    scanf("%d",&n);
    printf("\nENTER STUDENT'S INFORMATION\n");

// storing information
for (i = 0; i < n; ++i) 
{
    printf("\nEnter Student's Full Name: ");
    scanf("%s %s", s[i].firstName, s[i].lastName);
    printf("SCORES\n");
    printf("Quiz 1: ");
    scanf("%d", &s[i].q1);
    printf("Quiz 2: ");
    scanf("%d", &s[i].q2);
    printf("Quiz 3: ");
    scanf("%d", &s[i].q3);
    printf("Quiz 4: ");
    scanf("%d", &s[i].q4);
    printf("Quiz 5: ");
    scanf("%d", &s[i].q5);
    printf("Midterms (100pts): ");
    scanf("%d", &s[i].midterms);
    printf("Finals (100pts): ");
    scanf("%d", &s[i].finals);
    printf("\n");
}

//calculation
TotalQuiz = q1 + q2 +  q3 + q4 + q5;

QuizGrade = (TotalQuiz/50)*100*0.50;
MidtermExamGrade = (midterms/100)*100*0.20;
FinalExamGrade = (finals/100)*100*0.30;
FinalGrade = QuizGrade + MidtermExamGrade + FinalExamGrade;

// alphabetic equivalent
for(i = 0; i < n; i++)
{
    if(s[i].FinalGrade>=97 && s[i].FinalGrade<=100)
    {
        s[i].equigrade = "A+";
    }
    else if(s[i].FinalGrade>=93 && s[i].FinalGrade<=96)
    {
        s[i].equigrade = 'A';
    }
    else if(s[i].FinalGrade>=90 && s[i].FinalGrade<=92)
    {
        s[i].equigrade = "A-";
    }
    else if(s[i].FinalGrade>=87 && s[i].FinalGrade<=89)
    {
        s[i].equigrade = "B+";
    }
    else if(s[i].FinalGrade>=83 && s[i].FinalGrade<=86)
    {
        s[i].equigrade = 'B';
    }
    else if(s[i].FinalGrade>=80 && s[i].FinalGrade<=82)
    {
        s[i].equigrade = "B-";
    }
    else if(s[i].FinalGrade>=77 && s[i].FinalGrade<=79)
    {
        s[i].equigrade = "C+";
    }
    else if(s[i].FinalGrade>=73 && s[i].FinalGrade<=76)
    {
        s[i].equigrade = 'C';
    }
    else if(s[i].FinalGrade>=70 && s[i].FinalGrade<=72)
    {
        s[i].equigrade = "C-";
    }
}


printf("Displaying Information:\n\n");

// displaying information
for (i = 0; i < n; ++i) 
{
    printf("First name: %s %s\n", s[i].firstName, s[i].lastName);
    printf("Marks: %d\n", s[i].q1);
    printf("Marks: %d\n", s[i].q2);
    printf("Marks: %d\n", s[i].q3);
    printf("Marks: %d\n", s[i].q4);
    printf("Marks: %d\n", s[i].q5);
    printf("\n");
}
return 0;

}